PING))) Ultrasonic Range Finder

myztix

I was wondering if it was possible to measure the actual frequency received (echo) given that the ultrasonic sensor emits a pulse at 40kHz.

Thanks.

Phil Pilgrim (PhiPi)

Are you thinking Doppler? To get an accurate frequency determination, you would probably need a longer pulse than the short "pings" that are optimized for distance measurement.

-Phil

myztix

Yes, I was thinking Doppler, but can one actually measure the actual frequency using PING)))?

Phil Pilgrim (PhiPi)

No, not directly. If you find a pad to tap the return signal from, though, you might be able to hack something. But, again, I fear the pulse would be much too short to get a meaningful frequency reading.

-Phil

myztix

What exactly is the echo transducer (echo unit of the ultrasonic sensor) receiving from the return signal? Voltage? Resistance? Frequency?

allanlane5

I believe the mechanics are a piezo-electric element recieving the 'bounced' sound pulse. Which results in a voltage signal.

The BS2 interface is quite a ways away from this, though.

Bruce Bates

myztix -

On the Parallax web site (link below) there is a document named "BS-1 Applications Notes". In that document, on Page 53, you will find a schematic of an ultrasonic set up (transmitter and receiver) which uses the 555 timer, a couple of ultrasonic transducers, and a few other parts.

Link to the above named document:
http://www.parallax.com/ProductInfo/Microcontrollers/BASICStampDocumentation/tabid/440/Default.aspx

The example programs are for the BS-1 Stamp, and since you are using the BS-2 Stamp (a better and more powerful processor) the examples won't be of much use to you.

I hope that's helpful.

Regards,

Bruce Bates

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